Known joining staples for conveyor belts, belts, and similar products are composed of a top plate and a lower plate connected at one end by one or several narrower parts called knuckles, wherein the staples are mounted in alternating series at one end of the conveyor belt with a portion of the conveyor belt being disposed between the top plates and the lower plates of the staples in each series, and wherein the same operation is carried out again on the other end of the conveyor belt while shifting the knuckles of the second series of staples with respect to those of the first series so that the knuckles of the second series are engaged between the knuckles of the first series. A connecting and articulating rod is then engaged into one knuckle of a series of staples and then into one knuckle of the other series of staples and so on, thus making the equivalent of a hinge.
As regards the attaching of staples at the conveyor belt ends held between the top plate and lower plate of each joining staple, various means are used, with two means being the most common ones when considering the development of the related technology.
The most common staple attaching means consists of U-shaped clips made of round wire. Such clips include a back composed of a rectilinear round wire part extended at both ends by acute branches made of the same wire and bent at right angles with respect to the back. The spikes of the round wire branches are obtained by machining, i.e., milling or grinding. A second known means for attaching staples is composed of claws extending downward from the top plate of the staple. The clips made of U-shaped metal wire are inserted into holes provided in the top plate of the staples. The acute branches go through the end of the conveyor belt inserted between the top plate and the lower plate of the staple. The claws extending the top plate of the staple are directly inserted into the ends of the conveyor belt inserted between the two plates. Initially, the acute branches of the clips, when inserted through the thickness of the conveyor belt end, would meet corresponding holes provided in the other plate of the staple, then would go through such holes and be bent towards the outside of the lower plate of the staple. Similarly, the claws inserted along a similar path would also be bent towards the outside of the lower plate. This bend was made using an appropriately shaped matrix positioned under the lower plate.
The drawbacks of round wire clips lies in the fact that in order to have an excellent bending strength, it is necessary to increase the diameter of the clips. thus causing difficulties resulting from the thickness which could not be totally accommodated in a recess of the top plate of the staple and created problems with the scrapers. In addition, the clips made of round wire include branches, the end parts and spikes of which are made by grinding or milling and have mechanical properties that do not differentiate them from the rest of the clips, i.e., the back of the clips and the body of the branches. For bending the lower parts of the branches, steel wires are generally chosen, the mechanical properties of hardness and bending strength of which are intended to prevent breaking during the bending operations. Such properties are in contradiction with those that are required for the spikes of the branches to go without any difficulty and any deviation through the reinforcing frames of the elastomer material of the conveyor belts.
It should be noted that, on the clip-staple assembly of European Patent No. EP 0 464 399, that the staple is provided in the top portion thereof with a recess making it possible to accommodate most of the thickness of the back of the clip (See, e.g., FIG. 1). However, a small over-thickness that is likely to be hit by the scrapers remains. If it is desired to increase the diameter of the round wire clip to obtain better strength, the problem becomes impossible to solve since it would be necessary to increase the thickness of the top plate of the staple, which can also be hit by the scrapers. Thus, It should be understood that the clips made of round wire cannot be perfected because of their basic design.